Refining hydrometallurgical products containing precious metals.



To to whom it may concern UNITED PATENT: oFFIoE.

(ii-rarities w. MERRILL, F ALAMEDA, CALIFORNIA. REFlNlNGHYDROMETALLURGICAL PRODUCTS CONTAINING PRECIOUS METALS. I

Be it known that I, CHARLES W. MERRILL, a citizen of the United States,residing at Ala- 1'neda,'county of Alameda, State of California, haveinvented anlmproveinent in the Art of Refining IIydrometallurgicalProducts Containing Precious Metals; and I hereby declare the followingto be a full, clear, and. exact description of the same.

In refining finely-divided hydrometallurgical productssuclr asprecipitates. from c anid, chlorin, e ectrolytic deposits or, residuumby the ordinary method of cruoiblerefining difiiculties have beenencountered and lossesincurred on account, first,.of the line state ofdivision, often in the form of a fine dust; second, of the volatileconstituents often contained, as zinc and arsenic; third, ofthe.ab'sence, as a rule,

of a suitable collecting metal, as lead or copper, and, fourth, onaccount, of the absence of a suitable binding or adhesive agent. to pre'vent dust loss. In my process I overcome these dilliculties and lossesin the manner which I will hereinafter describe-and. claim.

.Where a solution of asoluble lead salt is mixed with the powderedmaterial prior to fusing, the effect is to envelop each individual dustparticle in a lead casing during fusion, The result is that eachprecious "particle is carried downward through the slag into thelead-bath.

I may briquet one or the other of the foregoing mixtures or addtheretoan adhesive.

agent, as molasses or lime, asa binder, or I may do both. In otherwords, I may under some conditions add to the linely'alivided materiallitharge a llux, a solution of a soluhle lead salt, and an adhesiveagent and then brir not the entire mixture.

'l lie object of briqueting, binding with an adhesive agent, andenveloping with a soluble lead salt is for the purpose of so iinitingthe naturally linely divided material into a coherent mass that duringthe introduction of the material to (he cupel, crucible, or othercontainer and during cupellation loss will not result, as occurs underordinary methods, by the linely-divided material beingcarried off in thel'orn-iof dry dust. This loss from dusting under ordinary methods ofrefining such productsamounts to from live to ten. per cent.--a-ser1ousmatter in practical re-lining on alarge scale, 1

or hyposulfite solutions or.

Patented March 20, 1906.

Having mixed and bound the material, I then fuse it in a cup'el orprueible, reduce the litharge to metallic lead, adding fresh materialperiodically. The lead collects and cont'ains the finely-dividedprecious metals and is then cu elled offend recovered as litliarge to beuse in subsequent operations' Thus the precious metals are obtainednearly pure and may be cast or remelted into bars.

The primary object of this invention is to prevent dust loss, asmentioned, and, secondly, it is for the purpose of reducing the amountof the values held over in the byproducts. By ordinary processes ofrecovery the slag often contains values to the extent of thousands ofdollars per ton. With my process the by-products are of very low value,

or the reason that the lead is-eonstantly per colating downward throughthe slag and carrying the values with it. To this end, it is preferredthat all themixed material should not be admitted at one charge into thecupel, but that in reducing any given quantity pertions of the bondedmixture should be added from time to time to the mass in the cupel, sothat the accumulating layer of slag will be subjected to successiveimpregnations of lead which will carry down values that would otherwisebeheld up by the slag.

The smelting steps of this process are conducted in a single I urnacei.a, a eupel-furnacethe slag being drawn off until .only the lead-bathremains,and curwllation is then proceeded with,.the residuum of preciousmetals being practically pure. e

Having thus described my invention, what I claim, and desire to cut,1S-- 7 The improvement in refining I 1nelv-d1v1ded secure by LettersPats hydrometallurgical products which consists.

in mixing the material with litharge, adding to said material or themixture a soluble lead salt, reducing the lit-.lmrge and soluble loadsalt to metallic lead by heat, replenishing the material periodically toprovide fresh accretions of lead, and finally cnpeling the lead off fromthe precious metals.

In witness whereof I have hereunto set my hand.

CHARLES w. MERRILL.

Witnesses:

S. H. Nounsn,

. Jicssnc (l. Snows.

